cfft3di,zfft3di(3F)					   cfft3di,zfft3di(3F)

NAME    [Toc]    [Back]

     cfft3di, zfft3di -	initialize the coefficient array for complex-tocomplex
 3D	FFT modules.

SYNOPSYS    [Toc]    [Back]

     FORTRAN SPECIFICATION
     subroutine	CFFT3DI( n1, n2, n3, coeff )
     integer		      n1, n2, n3
     complex		 coeff((n1+15) + (n2+15) + (n3+15))

     subroutine	ZFFT3DI( n1, n2, n3, coeff )
     integer		      n1, n2, n3
     double complex	 coeff((n1+15) + (n2+15) + (n3+15))

     C SPECIFICATION
     #include <fft.h>
     complex *cfft3di( int n1, int n2, int n3, complex *coeff);

     zomplex *zfft3di( int n1, int n2, int n3, zomplex *coeff);

DESCRIPTION    [Toc]    [Back]

     Initialize	the coefficient	array which is used in the 3D FFT modules.
     This array	contains the different twiddle factors and the factorization
     of	N1,N2 and N3 into prime	numbers.
     As	the FFT	modules	cfft3d or zfft3d only read the coeff array, it may be
     reused as many times as necessary once it has been	initialized.

     In	C, if ptr is NULL, cfft3di or zfft3di returns a	pointer	to an
     allocated buffer.

     CFFT3DI should be used to initialize the coefficient array	before any
     call to CFFT3D
     ZFFT3DI should be used to initialize the coefficient array	before any
     call to ZFFT3D

PARAMETERS    [Toc]    [Back]

     N1	- Integer, the first dimension size of the 3D sequence.	 Unchanged on
     exit.

     N2	- Integer, the second dimension	size of	the 3D sequence.  Unchanged on
     exit.

     N3	Integer, the third dimension size of the 3D sequence.  Unchanged on
     exit.

     COEFF - Array (C or Fortran) or NULL pointer(C).

Example	of Calling Sequence
     Initializing a coefficient	array for complex-to-complex FFTs of size
     200x300X125




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cfft3di,zfft3di(3F)					   cfft3di,zfft3di(3F)



     Fortran :
	  complex coeff((200+15)+(300+15)+(125+15))
	  call cfft3di(	200, 300, 125, coeff)

     C :
	  #include <fft.h>
	  complex *coeff;
	  coeff	= cfft3di( 200,	300, 125, NULL);

SEE ALSO    [Toc]    [Back]

	  fft, cfft3d, zfft3d


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